Skip to main content

takeWhile

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Returns an ImmVector containing the values of the current ImmVector up to but not including the first value that produces false when passed to the specified callback

public function takeWhile(
  (function(Tv): bool) $callback,
): ImmVector<Tv>;

That is, takes the continuous prefix of values in the current ImmVector for which the specified callback returns true.

The returned ImmVector will always be a subset (but not necessarily a proper subset) of the current ImmVector.

Parameters​

  • (function(Tv): bool) $callback

Returns​

Examples​

See Vector::takeWhile for usage examples.